Spazing Robot

[Al Skierkiewicz]

Matthew,
Let me chill one post above, there are no triacs in the speed controllers, the power devices are all power hexfets. They are able to be turned on and off better than triacs in DC circuits and have a lower "on" resistance. What you describe as the problem may have in fact been only related to your wiring, not that you moved the fans and corrected the problem. If the fans were wired to the supply side of the Victors (+12 and Gnd)) then you likely had a high resistance connection due to the addition of the fan wires/terminals. High resistance connections heat up with time and usually produce intermittant contact as they heat. It is a dominoe kind of effect. It is unlikely that the fans were drawing enough current to trip the breaker feeding each speed controller if you had wired the robot according to the manual. (You should not have been able to pass inspection if there was a problem with wiring.) I think what happened is you tightened the connections when you rewired the fan supply and that corrected the original problem. The fans provide some cooling to the power devices but they already are pretty efficient little beasties. Remember that the speed controllers are operating in an "H" configuration so only two of the four banks are on at one time. If you are using a tank tread drive the speed contollers could get warm after a two minute match but if the fans are wired as speced in the manual, the fans should be running the minute you turn the robot on. Since there is not a lot of thermal mass in the contoller, the fans ought to do a good job of cooling before you retrieve your robot at the end of a match.